It is unfortunate that parrots get many of the same illnesses that we humans do - but they are not as easy to diagnose in a bird. I often wonder how many of our very beloved birds who are found dead or deathly ill have been struck down by heart disease (my girl has congestive heart disease and atherosclerosis), liver disease, kidney disease, stroke, seizures, pancreatitis..... etc.. They can't tell us where they hurt or when they just feel bad, so we have to guess. Our vets, although they do their best, don't have the tools that human, dog and cat vets have. There is very little clinical research on parrots. Much of the time they too must just use their best guess to treat our babies.
Fly free and high little guy.